Which compound is 3-amino-2-methylbutanoic acid?
CH3CH(NH2)CH(CH3)COOH\text{CH}_3\text{CH}(\text{NH}_2)\text{CH}(\text{CH}_3)\text{COOH}CH3CH(NH2)CH(CH3)COOH
CH3CH2C(CH3)(NH2)COOH\text{CH}_3\text{CH}_2\text{C}(\text{CH}_3)(\text{NH}_2)\text{COOH}CH3CH2C(CH3)(NH2)COOH
H2NCH2CH(CH3)CH2COOH\text{H}_2\text{NCH}_2\text{CH}(\text{CH}_3)\text{CH}_2\text{COOH}H2NCH2CH(CH3)CH2COOH
CH3CH(NH2)CH2CH2COOH\text{CH}_3\text{CH}(\text{NH}_2)\text{CH}_2\text{CH}_2\text{COOH}CH3CH(NH2)CH2CH2COOH